Earlier generation compounds of nitrogen-containing bisphosphonates such as pamidronate (Aredia®), alendronate (Fosamax®), risedronate (Actonel®), zoledronate (Zometa®), and ibandronate (Boniva) represent important drugs currently used to treat conditions such as osteoporosis, Paget's disease and hypercalcemia due to malignancy. These compounds function primarily by inhibiting the enzyme farnesyl diphosphate synthase (FPPS), resulting in decreased levels of protein prenylation in osteoclasts. Certain bisphosphonates have also been found to have anti-parasitic activity and to stimulate human γδ T cells, and there is interest in cancer-related applications. There is continued interest, however, in the further development of alternative bisphosphonate compounds and methods of use such as therapeutic applications.
There have been reports regarding the significance of certain nitrogen-containing groups in the context of active bisphosphonate compounds. See US Publication 20060079487 and PCT Publication WO/2006/039721. The present invention discloses the fact that, remarkably, bisphosphonates lacking certain nitrogen-containing groups but containing instead aryl, substituted aryl, sulfonium and phosphonium groups have activity in killing cancer cells, in inhibiting the enzyme farnesyl diphosphate synthase from humans as well as from Trypanosoma brucei (the causative agent of African sleeping sickness), in stimulating gamma delta T cells in the human immune system, as well as acting as inhibitors of the enzyme undecaprenyl diphosphate synthase, essential for cell wall biosynthesis in many pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. As such, these novel compounds are of interest in the context of the treatment of cancer, bone resorption diseases and infectious diseases caused by bacteria and protozoa.